I just discovered with the new OS that Osc 2 is not being muted when selecting a patch with FM 2->1 selected.
If I then toggle the FM 2->1 off and back on, the Osc 2 does get muted correctly.
I tried rewriting the patch after doing this, but that didn't fix it either. Rewriting the patch makes it happen again, until toggling FM 2->1 off and back on again.
EDIT: Turning on Osc 2 Filter Bypass fixes this.